Editing Water quality (section)

===Human consumption===
[[File:Chemical contamination of drinking water.jpg|upright=1.4|thumb|Regional and national contamination of drinking water by chemical type and population size at risk of exposure]]
Contaminants that may be in untreated water include [[microorganism]]s such as [[virus]]es, [[protozoa]] and [[bacteria]]; [[Inorganic compound|inorganic]] contaminants such as [[Salt (chemistry)|salts]] and [[metals]]; [[Organic compound|organic chemical]] contaminants from industrial processes and [[petroleum]] use; [[pesticides]] and [[herbicides]]; and [[radioactive]] contaminants. Water quality depends on the local [[geology]] and [[ecosystem]], as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a [[heat sink]], and overuse (which may lower the level of the water).{{Citation needed|date=October 2022}}

The [[United States Environmental Protection Agency]]<ref>{{Cite web |title=What is water quality? Eight key characteristics |url=https://waterrangers.ca/what-is-water-quality/ |access-date=2022-11-10 |website=Water Rangers |language=en-US}}</ref> (EPA) limits the amounts of certain contaminants in [[tap water]] provided by US [[public water system]]s. The [[Safe Drinking Water Act]] authorizes EPA to issue two types of standards:
* ''primary standards'' regulate substances that potentially affect human health;<ref>U.S. Environmental Protection Agency (EPA), Washington, D.C. "National Primary Drinking Water Regulations." ''Code of Federal Regulations,'' {{uscfr|40|141}}.</ref><ref name="EPA DW reqts">{{cite web |url=https://www.epa.gov/dwreginfo/drinking-water-regulations |title=Drinking Water Regulations |author=<!--Not stated--> |date=2022-09-20 |website=Drinking Water Requirements for States and Public Water Systems |publisher=EPA}}</ref>
* ''secondary standards'' prescribe aesthetic qualities, those that affect taste, odor, or appearance.<ref>{{cite web |url=https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals |title=Secondary Drinking Water Standards: Guidance for Nuisance Chemicals |author=<!--Not stated--> |date=2022-02-17 |publisher=EPA}}</ref>

The U.S. [[Food and Drug Administration]] (FDA) regulations establish limits for contaminants in [[bottled water]]. <!--{{fv}}: must provide the same protection for public health.--><ref>{{cite web |url=https://www.fda.gov/Food/FoodborneIllnessContaminants/BuyStoreServeSafeFood/ucm046894.htm |archive-url=https://web.archive.org/web/20130414233847/http://www.fda.gov/Food/FoodborneIllnessContaminants/BuyStoreServeSafeFood/ucm046894.htm |url-status=dead |archive-date=14 April 2013 |title=FDA Regulates the Safety of Bottled Water Beverages Including Flavored Water and Nutrient-Added Water Beverages |author=<!--Not stated--> |date=2018-09-22 |website=Food Facts for Consumers |publisher=U.S. Food and Drug Administration |location=Silver Spring, MD}}</ref> Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of these contaminants does not necessarily indicate that the water poses a health risk.

In [[urbanization|urbanized]] areas around the world, [[water purification]] technology is used in municipal water systems to remove contaminants from the source water (surface water or [[groundwater]]) before it is distributed to homes, businesses, schools and other recipients. Water drawn directly from a stream, lake, or [[aquifer]] and that has no treatment will be of uncertain quality in terms of potability.<ref name="WHO DW quality"/>

The burden of polluted drinking water disproportionally effects under-represented and vulnerable populations.<ref>{{cite book |last1=Katner |first1=A. L. |last2=Brown |first2=K |last3=Pieper |first3=K. |last4=Edwards |first4=M |last5=Lambrinidou |first5=Y |last6=Subra |first6=W. |editor-last1=Brinkmann |editor-first1=R. |editor-last2=Garren |editor-first2=S. |date=2018 |chapter=America’s Path to Drinking Water Infrastructure Inequality and Environmental Injustice: The Case of Flint, Michigan |title=The Palgrave Handbook of Sustainability |publisher=Palgrave Macmillan |location=London |pages=79–97 |doi=10.1007/978-3-319-71389-2_5|isbn=978-3-319-71388-5 }}</ref> Communities that lack these clean drinking-water services are at risk of contracting water-borne and pollution-related illnesses like Cholera, [[diarrhea]], dysentery, hepatitis A, typhoid, and polio.<ref>{{cite web |title=Drinking-water |url=https://www.who.int/en/news-room/fact-sheets/detail/drinking-water |date=2022-03-21 |publisher=WHO |id=Fact sheet}}</ref> These communities are often in low-income areas, where human wastewater is discharged into a nearby drainage channel or surface water drain without sufficient treatment, or is used in agricultural irrigation.